package max;



 class TreeNode {
     int val;
     TreeNode left;
     TreeNode right;
     TreeNode() {}
     TreeNode(int val) { this.val = val; }
     TreeNode(int val, TreeNode left, TreeNode right) {
         this.val = val;
         this.left = left;
         this.right = right;
     }
 }
class Solution {
    public int maxDepth(TreeNode root) {
        if (root == null){
            return 0;
        }else {
            int left = maxDepth(root.left);
            int right = maxDepth(root.right);
            return Math.max(left,right)+1;
        }

     }


}